1. Forster, P. et al. in IPCC Climate Change 2007: The Physical Science Basis (eds Solomon, S. et al.) 129–234 (Cambridge Univ. Press, 2007).
2. Prather, M. et al. in IPCC Climate Change 2001: The Scientific Basis (eds Houghton, J. et al.) 240–287 (Cambridge Univ. Press, 2001).
3. Mosier, A. et al. Closing the global N2O budget: Nitrous oxide emissions through the agricultural nitrogen cycle. Nutr. Cycl. Agroecosys. 52, 225–248 (1998).
4. Crutzen, P. J. & Ehhalt, D. H. Effects of nitrogen fertilizers and combustion on the stratospheric ozone layer. Ambio 6, 112–117 (1977).
5. IFA Sustainable Management of the Nitrogen Cycle in Agriculture and Mitigation of Reactive Nitrogen Side Effects (International Fertilizer Industry Association, 2007); available at < http://www.fertilizer.org/ifa/form/pub_lat.asp >.